Adjustable front caster mount assembly for a wheelchair

ABSTRACT

A caster mount assembly for a front caster of a wheelchair. The assembly includes a first rotatable body having a first plurality of non-uniformly spaced apart apertures and a second rotatable body having a second plurality of non-uniformly spaced apart apertures. The first and second rotatable bodies may be rotated relative to one another along a common axis of rotation to align a selected one of the first apertures with a selected one of the second apertures. The first rotatable body is non-rotatably coupled to the second rotatable body by a first coupler after the selected first aperture and second aperture have been aligned. A bearing fork assembly is non-rotatably coupled to the second rotatable body for rotation therewith. The second rotatable body may be rotated to orient an upright pivot pin of the bearing fork assembly substantially perpendicular to a support surface.

CROSS REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional Application No.61/312,239, filed Mar. 9, 2010, which is incorporated herein in itsentirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention is directed generally to front wheel caster mountassemblies for use with a wheelchair and more particularly to angleadjusting front wheel caster mount assemblies for use with a wheelchair.

2. Description of the Related Art

A typical wheelchair includes a seat supported by a frame resting uponfour wheels. A front wheel and a rear wheel are disposed on each side ofthe wheelchair. The pair of rear wheels may be located under or behind aseat upon which the occupant of the wheelchair is seated. The frontwheels are located in front of the rear wheels and pivot to facilitatesteering. Generally, the rear wheels are mounted to opposite sides ofthe frame by an axle assembly. Generally, the front wheels are mountedto opposite sides of the frame by a bearing fork assembly.

In many wheelchair designs, the front wheels have a significantlysmaller radius than the rear wheels. Therefore, the axles of the rearwheels are typically mounted to the frame at locations that are elevatedfrom the locations of attachment of the axles of the front wheels to theframe. In this manner, an angle of the frame relative to the ground maybe determined by the locations in which the front and rear wheels aremounted to the frame and the diameter of the front and rear wheels.

An angle is defined between the frame and the ground. For front and rearwheels each having a predetermined and substantially constant diameter,the angle may be determined by the attachment location of the frontwheels relative to the attachment location of the rear wheels. Becauseit may be desirable to level the seat relative to the ground (i.e.,adjust the angle of the seat relative to the ground to approximatelyzero degrees) in some wheelchair designs, the vertical and/or horizontalpositions of the rear and/or front wheels relative to the frame may beadjusted to achieve a level seat position.

Each of the front wheels is mounted to the longitudinal frame member bya bearing fork assembly. In many wheelchair designs, the bearing forkassembly includes a bearing fork and an upright pivot pin, which may beimplemented as a stem bolt. The bearing fork is coupled to an axle aboutwhich the front wheel rotates. The upright pivot pin pivotably couplesthe bearing fork to the frame. To steer the wheelchair, the bearing forkpivots about the upright pivot pin.

As a general rule, it is desirable to orient the upright pivot pingenerally perpendicular to the ground. If the upright pivot pin is notperpendicular to the ground, the front wheels may not pivot properly.Further, because the front wheels typically pivot to facilitate steeringthe wheelchair, if the upright pivot pin is not perpendicular to theground, the front wheel may not rotate properly and the steering of thewheelchair may be impaired.

A wheelchair may require adjustment to fit a particular user. Forexample, many wheelchairs allow the user to adjust the height of theseat by vertically moving the location where the frame attaches to therear axles. This adjustment will typically modify the angle of the seatrelative to the ground. Similarly, some wheelchair designs allow a userto move the rear wheels longitudinally forward and backward relative tothe seat, which may also modify the angle of the seat.

The ability to change the angle of the seat is important to properpositioning of the wheelchair occupant. Increasing the angle of the seat(i.e., increasing the height of the front of the seat relative to theback of the seat) allows gravity to help prevent the occupant of thewheelchair, who will likely have limited or no lower extremity functionand perhaps limited trunk muscular control, from sliding out of theseat.

Often, finding the correct angle of the seat is a matter of trial anderror. Over time, the most desirable angle may change. For example, aparticular wheelchair user may have a degenerative disease that requiresincreasing the angle over time. Alternatively, as people age they becomemore susceptible to pressure sores. By reducing the angle of the seat,it is possible to reduce the pressure on the buttocks.

Unfortunately, if the angle of the frame relative to the ground ischanged, the angle of the upright pivot pins of the bearing forkassemblies may require adjustment to reorient the upright pivot pinsperpendicular to the ground. Therefore, a need exists for devices thatrotate the upright pivot pins to which the bearing forks are mounted toposition the upright pivot pins perpendicular to the ground.

The bearing fork may have one tine (a mono-fork) or two tines. In manyprior art mono-fork designs, a proximal end of an axle is connected tothe tine by a fastener that passes through a transverse hole formed inthe proximal end of the axle. Unfortunately, the transverse hole weakensthe axle and is often the location of a failure. Therefore, a mono-forkdesign that does not include a transverse hole is desirable.

The present application provides these and other advantages as will beapparent from the following detailed description and accompanyingfigures.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

FIG. 1 is an elevational perspective view of a wheelchair.

FIG. 2 is an perspective view of an underside of the wheelchair of FIG.1.

FIG. 3A is an exploded perspective view of a left bearing fork assemblyand a left angle adjusting caster mount assembly of the wheelchair ofFIG. 1.

FIG. 3B is an exploded perspective view the left bearing fork assemblyand the left angle adjusting caster mount assembly of the wheelchair ofFIG. 1.

FIG. 3C is an exploded side view of an axle and a section view of a tineof a fork of the left bearing fork assembly of FIGS. 3A and 3B.

FIG. 4 is an enlarged exploded perspective view the left angle adjustingcaster mount assembly of the wheelchair of FIG. 1.

FIG. 5 is a sectional view of the left bearing fork assembly and theleft angle adjusting caster mount assembly of the wheelchair of FIG. 1.

FIG. 6 is a perspective view of an alternate embodiment of a leftbearing fork assembly including a conventional fork and axle assembly.

FIG. 7 is an exploded view of the left bearing fork assembly of FIG. 6.

FIG. 8 is a first side view of an inner end cap of the left angleadjusting caster mount assembly of the wheelchair of FIG. 1.

FIG. 9 is a second side view of the inner end cap of the left angleadjusting caster mount assembly of the wheelchair of FIG. 1.

FIG. 10 is a side view of a caster mount of the left angle adjustingcaster mount assembly of the wheelchair of FIG. 1.

FIG. 11 is a first side view of the left bearing fork assembly and theleft angle adjusting caster mount assembly of the wheelchair of FIG. 1illustrated with an upright pivot pin of the left bearing fork assemblyangled rearwardly.

FIG. 12 is a first side view of the left bearing fork assembly and theleft angle adjusting caster mount assembly of the wheelchair of FIG. 1illustrated with the upright pivot pin of the left bearing fork assemblyangled forwardly.

FIG. 13 is a first side view of the left bearing fork assembly and theleft angle adjusting caster mount assembly of the wheelchair of FIG. 1illustrated with the upright pivot pin of the left bearing fork assemblyangled perpendicularly with respect to a support surface.

FIG. 14 is a sectional view of the wheelchair of FIG. 1 having its leftrear wheel in a first position relative to a frame.

FIG. 15 is a sectional view of the wheelchair of FIG. 1 having its leftrear wheel in a second position relative to the frame.

FIG. 16 is a perspective view an embodiment of a left caster mountassembly that is not configured to adjust the angle of the upright pivotpin of the left bearing fork assembly relative to the support surface.

FIG. 17 is an exploded view of the left caster mount assembly of FIG.16.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is an elevational view of an exemplary wheelchair 100 supportedby a support surface 102 (e.g., the ground). FIG. 2 provides a view ofthe underside of the wheelchair 100. Referring to FIGS. 1 and 2, thewheelchair 100 includes a frame 120 having a right side portion 122 anda left side portion 124 as perceived by an occupant of the wheelchair100. Referring to FIG. 2, in the embodiment illustrated, the right sideportion 122 includes a right frame member 126 having a generallyhorizontally extending portion 130 and a generally downwardly extendingportion 132. The right frame member 126 may be implemented as hollowtube bent to define the portions 130 and 132. The left side portion 124includes a left frame member 128 having a generally horizontallyextending portion 134 and a generally downwardly extending portion 136.The left frame member 128 may be implemented as hollow tube bent todefine the portions 134 and 136. The horizontally extending portions 130and 134 of the right and left frame members 126 and 128, respectively,are illustrated as being substantially parallel to one another.

Referring to FIG. 1, the wheelchair 100 includes a seat 138 supported bythe frame 120. In the embodiment illustrated, the seat 138 is coupled tothe right and left support members 126 and 128 and extends therebetween.Optionally, a footrest 140 may be coupled to the frame 120 in any mannerknown in the art. In the embodiment illustrated, the footrest 140 iscoupled to the generally downwardly extending portions 132 and 136 ofthe right and left frame members 126 and 128, respectively.

The wheelchair 100 has a right rear wheel 142 and a left rear wheel 144.The right and left rear wheels 142 and 144 each rotate relative to theframe 120 about an axle assembly 146. The axle assembly 146 of the rightrear wheel 142 is coupled to a first end 147 of a camber tube 148 andthe axle assembly 146 of the left rear wheel 144 is coupled to a secondend 149 of the camber tube 148.

Referring to FIG. 2, the first end 147 of the camber tube 148 is coupledto the right side portion 122 of the frame 120 by a right rear wheelmounting assembly 152 and the second end 149 of the camber tube 148 iscoupled to the left side portion 124 of the frame 120 by a left rearwheel mounting assembly 154. The right and left rear wheel mountingassemblies 152 and 154 may be constructed in any manner known in the artfor coupling the camber tube 148 to the frame 120 and the presentapplication is not limited to the exemplary right and left rear axleassemblies 152 and 154 depicted in the figures. Further, the presentapplication is not limited to use with wheelchairs including a cambertube. For example, the wheelchair 100 may be implemented as a foldingwheelchair without a camber tube extending between the right and leftsides of the wheelchair.

Returning to FIG. 1, the wheelchair 100 has a right front wheel 162attached to the right side portion 122 of the frame 120 and a left frontwheel 164 attached to the left side portion 124 of the frame 120. Theleft and right front wheels 162 and 164 are substantially identical ormirror images of one another. Therefore, for the sake of brevity, onlythe left front wheel 164 will be described in more detail. Returning toFIGS. 3A and 3B, the left front wheel 164 may include one or morebearings 165. By way of a non-limiting examples, each of the bearings165 (see FIGS. 3A and 3B) may have an opening 167. Depending upon theimplementation details, the opening 167 may have a diameter of about ⅜inches (0.375 inches).

In the embodiment illustrated, a right connecting strut 156 (illustratedin FIG. 2) is connected to the generally downwardly extending portion132 of the right frame member 126 and a left connecting strut 158 isconnected to the generally downwardly extending portion 136 of the leftframe member 128. The right and left connecting struts 156 and 158 areillustrated as being mirror images of one another.

In the embodiment illustrated, the right front wheel 162 is coupled tothe right connecting strut 156 by a right bearing fork assembly 172 andthe left front wheel 164 is coupled to the left connecting strut 158 bya left bearing fork assembly 174. The right and left bearing forkassemblies 172 and 174 are mirror images of one another. Therefore, forthe sake of brevity, only the left bearing fork assembly 174 will bedescribed in detail.

Referring to FIGS. 3A and 3B, the left bearing fork assembly 174includes a top cap 176, an upright pivot pin 180, one or more bearings184, an optional retaining ring 186, and a fork 190. The top cap 176 maybe generally ring-shaped having a central aperture 177. The top cap 176may have a contoured upper surface 179 and a lower portion 173 oppositethe contoured upper surface 179.

Turning to FIG. 4, the upright pivot pin 180 may be generallycylindrical in shape with a circular cross-sectional shape. The uprightpivot pin 180 has a first end portion 181 opposite a second end portion182. A transverse threaded through-hole 183 is formed in the first endportion 181. The second end portion 182 may be relieved relative to thefirst end portion 181 to define an overhanging stop wall 185. Outsidethreads 187 are disposed about the second end portion 182.

In the embodiment illustrated in FIGS. 3A and 3B, the bearings 184include a first bearing 184A and a second bearing 184B. The bearings184A and 184B may be ring-shaped having centrally positioned openings189A and 189B. The upright pivot pin 180 may pass through the openings189A and 189B. The optional retaining ring 186 may be disposed betweenthe bearings 184A and 184B.

As illustrated in FIGS. 1-3B, 5, and 11-17, the fork 190 may include asingle tine 192. In such embodiments, the fork 190 is referred to as amono-fork 194. At least one threaded aperture (e.g., threaded apertures193A and 193B) is formed in the tine 192. As is apparent to those ofordinary skill in the art, inside threads have a maximum diameter and aminimum diameter. Similarly, outside threads also have a maximumdiameter and a minimum diameter.

The tine 192 illustrated in FIG. 3C includes the threaded apertures 193Aand 193B. Each of the threaded apertures 193A and 193B has a largerdiameter portion 197A without threads adjacent a smaller diameterthreaded portion 197B. The larger diameter portion 197A has a diameter“D-1” and the smaller diameter portion 197B has a maximum diameter“D-2.” The diameter “D-1” is larger than the diameter “D-2.” By way of anon-limiting example, the diameter “D-1” may be about 0.469 inches.

The mono-fork 194 includes a collar portion 196 connected to the tine192. Referring to FIG. 5, the collar portion 196 has a continuoussidewall 197 having an open upper end 198 and an open lower end 199. Thesidewall 197 has an inwardly facing surface 200 opposite an outwardlyfacing surface 201. The inwardly facing surface 200 defines a hollowinterior 202.

Along the inwardly facing surface 200, a relieved portion 203 is formedin the sidewall 197. The relieved portion 203 extends downwardly fromthe open upper end 198 and terminates before reaching the open lower end199. The relieved portion 203 is sized and shaped to receive thebearings 184 and the optional retaining ring 186. A stop wall 204 isformed along the bottom of the relieved portion 203 above the open lowerend 199. The bearings 184 rest upon the stop wall 204 when the bearings184 are received inside the relieved portion 203. Optionally, aninterior groove 205 is formed in the relieved portion 203. The interiorgroove 205 is configured to receive the optional retaining ring 186positioned between the bearings 184A and 184B.

An exterior groove 206 is formed in the outwardly facing surface 201 ofthe sidewall 197 below the open upper end 198. The sidewall 197 isgenerally cylindrical in shape. The exterior groove 206 extends alongthe outer circumference of the sidewall 197. In the embodimentillustrated in FIGS. 3A and 3B, the exterior groove 206 is positionedbetween the open upper end 198 and the tine 192.

The lower portion 173 of the top cap 178 is configured to rest upon theopen upper end 198 of the sidewall 197. In the embodiment illustrated,the upright pivot pin 180 extends through the central aperture 177 ofthe top cap 176 and into the open upper end 198 of the sidewall 197. Theupright pivot pin 180 passes through the opening 189A of the bearing184A, the optional retaining ring 186, and the opening 189B of thebearing 184B, to exit the hollow interior 202 (see FIG. 5) through theopen lower end 199. The collar portion 196 is configured to rotate aboutthe upright pivot pin 180, which is aligned along a steering axis. Thus,the fork 190 is rotatable about a steering axis.

A fastener 207 (such as a nut) is coupled to the second end portion 182of the upright pivot pin 180 to retain it inside the hollow interior 202(see FIG. 5) of the collar portion 196. In the embodiment illustrated,the fastener 207 is implemented as a nut configured to threadedly engagethe outside threads 187 (see FIG. 4) formed on the second end portion182 of the upright pivot pin 180. A washer 208 may be disposed betweenthe fastener 207 and the open lower end 199 of the sidewall 197. Whenthe fastener 207 is tightened on the second end portion 182 of theupright pivot pin 180, the washer 208 bears against the bearing 184B,which in turn, may bear against the optional retaining ring 186. Becausethe optional retaining ring 186 is retained inside the interior groove205, the retaining ring 186 may prevent the upright pivot pin 180 fromexiting the hollow interior 202 of the collar portion 196 through theopen upper end 198.

A bumper 209 is positioned inside the exterior groove 206. By way of anon-limiting example, the bumper 209 may be implemented as an o-ring.The bumper 209 is positioned to protect the left bearing fork assembly174 from damage caused by collisions with objects such as walls, doors,steps, and the like. The bumper 209 may help prevent damage to suchother objects from impact with the left bearing fork assembly 174.

Returning to FIGS. 3A and 3B, the left front wheel 164 is rotatablyconnected to the mono-fork 194 by a left axle assembly 212. The leftaxle assembly 212 includes an axle 213 having a threaded proximal endportion 214 opposite a distal end portion 215.

Turning to FIG. 3C, the distal end portion 215 may be generallycylindrical in shape with a circular cross-sectional shape. By way of anon-limiting example, the distal end portion 215 may have a diameter“D-3” of about 0.374 inches. The opening 167 (see FIGS. 3A and 3B) ofthe bearings 165 (see FIGS. 3A and 3B) is configured to receive thedistal end portion 215 of the axle 213. The opening 167 may have adiameter of about ⅜ inches (0.375 inches).

Turning to FIG. 3C, the threaded proximal end portion 214 has a maximumdiameter “D-4” and a minimum diameter “D-5.” In the embodimentillustrated, the minimum diameter “D-5” is larger than the diameter“D-3” of the distal end portion 215. This configuration may improve thestrength of the axle 213 where the axle 213 is threaded into the fork192. By way of a non-limiting example, the maximum diameter “D-4” may beabout 0.437 inches.

The axle 213 may include a relieved portion “REL” adjacent the threadedproximal end portion 214. By way of a non-limiting example, the relievedportion “REL” may have a diameter of about 0.370 inches. The relievedportion “REL” may be configured to relieve mechanical stress in thethreaded proximal end portion 214 caused by the threading of theproximal end portion 214 in to a selected one of the threaded apertures193A or 193B.

The axle 213 may include a first stop portion 211A adjacent the distalend portion 215 configured to limit the lateral movement of the leftfront wheel 164 along the distal end portion 215. The axle 213 may alsoinclude a second stop portion 211B having a larger diameter than theother portions of the axle 213. The second stop portion 211B isconfigured to contact a portion of the tine 192 adjacent the selectedone of the threaded apertures 193A or 193B to halt the inward movementof the threaded proximal end portion 214 into the selected aperture.

An intermediate portion “INT” may be disposed between the relievedportion “INT” and the second stop portion 211B. The intermediate portion“INT” may have a diameter “D-6” that is approximately equal to thediameter “D-1” of the larger diameter portion 197A.

The axle 213 may include a tapered portion “TAP” between the first andsecond stop portions 211A and 211B.

The axle 213 may be substantially solid with an inwardly longitudinallyextending threaded channel 217 having inside threads formed in thedistal end portion 215. The threaded proximal end portion 214 isconfigured to be threaded into a selected one of the threaded apertures193A or 193B formed in the tine 192.

As discussed above, in the embodiment illustrated, each of the threadedapertures 193A and 193B includes the larger diameter unthreaded portion197A adjacent the smaller diameter threaded portion 197B. The threadedproximal end portion 214 is inserted through the larger diameter portion197A and threaded into the smaller diameter portion 197B of the selectedone of the threaded apertures 193A or 193B. When fully threaded into thesmaller diameter portion 197B, the intermediate portion “INT” (which hasapproximately the same diameter as the larger diameter portion 197A) iseffectively press fit or forced into the larger diameter portion 197A ofthe selected one of the threaded apertures 193A or 193B. Thisconfiguration is substantially stronger than a configuration in whichthe axle 213 is simply threaded into the mono-fork 194 without the pressfit.

The axle 213 may be configured to have greater strength than prior artaxles used with other mono-forks. Typically, the location of greateststress along the axle 213 occurs at the junction of the axle 213 withthe fork 192. The second stop portion 211B provides an increased amountof mass at or near that location, which improves the strength of theaxle 213. Other aspects of the axle 213 that alone and in combinationwith other features may increase the strength of the axle 213 includethe press fit between the intermediate portion “INT” and the largerdiameter portion 197A, and the threaded proximal end portion 214 havingthe minimum diameter “D-5” that is larger than the diameter “D-3” of thedistal end portion 215. In particular implementations, all or a subsetof the above strength improving features may be incorporated into theaxle 213 to provide a mono-fork and axle combination that issubstantially stronger than prior art mono-fork and axle combinations.

The threaded proximal end portion 214 may be permanently bonded insidethe selected one of the threaded apertures 193A or 193B. For example, achemical bonding agent or adhesive, such as LOCTITE® 262 Threadlocker,may be used to permanently bond the threaded proximal end portion 214inside the selected one of the threaded apertures 193A or 193B.

The left axle assembly 212 also includes a fastener 218 and an end cap219. The fastener 218 may be implemented as a screw, bolt, and the like.The fastener 218 is configured to be coupled to the distal end portion215 of the axle 213 and when so coupled to press the end cap 219 againsta side portion of the left front wheel 164. In the embodimentillustrated, the fastener 218 has outside threads configured tothreadedly engage the threaded channel 217 formed in the distal endportion 215 of the axle 213.

Alternatively, referring to FIGS. 6 and 7, the fork 190 may beimplemented as a conventional fork 195 having a first tine 192A spacedapart from a second tine 192B. The first and second tines 192A and 192Bare both coupled to the collar portion 196. The first tine 192A includesone or more through-holes (e.g., through-holes 220A-220C) and the secondtine 192B includes one or more through-holes (e.g., through-holes221A-221C) juxtaposed with the through-holes of the first tine 192A. Theleft front wheel 164 is rotatably connected to the conventional two-tinefork by a conventional left axle assembly 222. The conventional leftaxle assembly 222 includes an axle 224 configured to be received insidea pair of juxtaposed through-holes (e.g., the through-holes 220A and221A) formed in the tines 192A and 192B to rotatably couple the leftfront wheel 164 between the tines 192A and 192B. The conventional leftaxle assembly 222 may also include a fastener 223A and an end cap 225Afor coupling one end of the axle 224 to the tine 192A and a fastener223B and an end cap 225B for coupling the other end of the axle 224 tothe tine 192B. The fasteners 223A and 223B may be substantially similarto the fastener 218. The end caps 225A and 225B may be substantiallysimilar to the end cap 219.

Optionally, referring to FIGS. 1 and 2, a generally horizontallyoriented right collar or caster barrel 226 may be coupled to the rightconnecting strut 156 and a left caster barrel 228 may be coupled to theleft connecting strut 158. In the embodiment illustrated in FIGS. 1 and2, the right connecting strut 156 is curved and extends between thecaster barrel 226 and the generally downwardly extending portion 132 ofthe right frame member 126. Similarly, the left connecting strut 158 iscurved and extends between the caster barrel 228 and the generallydownwardly extending portion 136 of the right frame member 128.

The caster barrels 226 and 228 are mirror images of one another.Therefore, for the sake of brevity, only the left caster barrel 228 willbe described in detail. Referring to FIG. 4, the left caster barrel 228is generally cylindrically shaped having a continuous sidewall 230defining a hollow interior 231. As may be seen in FIGS. 3A and 3B, thecontoured upper surface 179 of the top cap 176 is configured to matewith the sidewall 230 of the caster barrel 228.

The sidewall 230 has a first open end portion 232 opposite a second openend portion 234. Spaced apart notches or cutout portions “N-1” to “N-6”(see FIG. 3A) are formed in the edge of the sidewall 230 along the firstopen end portion 232. The left connecting strut 158 is affixed to thesidewall 230. An elongated aperture or slot 240 is formed in thesidewall 230 at a location spaced apart circumferentially from where theleft connecting strut 158 is affixed to the sidewall 230. The slot 240is shaped and sized to allow the upright pivot pin 180 to passtherethrough and to be rotated or pivoted inside the slot 240 forwardlyand rearwardly.

Referring to FIG. 2, in embodiments in which the caster barrels 226 and228 are coupled to the right and left connecting struts 156 and 158,respectively, the right and left bearing fork assemblies 172 and 174 maybe connected to the right and left caster barrels 226 and 228,respectively, by right and left angle adjusting caster mount assemblies252 and 254, respectively. The right and left angle adjusting castermount assemblies 252 and 254 are mirror images of one another.Therefore, for the sake of brevity, only the left caster mount assembly254 will be described in detail.

The left caster mount assembly 254 includes an inner end cap 262 and ancaster mount 264. Referring to FIG. 4, the inner end cap 262 isgenerally disc-shaped having a center portion 270 surrounded by aperipheral portion 274. Turning to FIG. 8, a position marker 276 isprovided on the peripheral portion 274. In the embodiment illustrated,the position marker 276 has been implemented as a cutout portion formedon the outermost edge of the peripheral portion 274.

A center through-hole 278 is formed in the center portion 270. One ormore through-holes (e.g., through-holes “A-1” to “A-6”) are formed inthe peripheral portion 274. In the embodiment illustrated, sixthrough-holes “A-1” to “A-6” are formed in the peripheral portion 274.The through-holes “A-1” and “A-2” are approximately 59° apart. Thethrough-holes “A-2” and “A-3” are approximately 59° apart. Thethrough-holes “A-3” and “A-4” are approximately 59° apart. Thethrough-holes “A-4” and “A-5” are approximately 59° apart. Thethrough-holes “A-5” and “A-6” are approximately 59° apart. Thethrough-holes “A-1” and “A-6” are approximately 65° apart. Thus, the sixthrough-holes “A-1” to “A-6” are not equally spaced apart. The positionmarker 276 is illustrated as being positioned adjacent to thethrough-hole “A-1.”

Turning to FIG. 9, the inner end cap 262 has a body portion 280 and agraspable outer portion 282. The body portion 280 is configured to bereceived inside the first open end portion 232 of the caster barrel 228.When the body portion 280 is received inside the caster barrel 228, thegraspable outer portion 282 remains outside the hollow interior 231defined by the sidewall 230. Thus, the graspable outer portion 282 isaccessible to a user. The position marker 276 is formed in the graspableouter portion 282.

The body portion 280 of the inner end cap 262 includes a plurality ofoutwardly extending teeth or projections (e.g., projections “T-1” to“T-6”) arranged circumferentially around the outer edge of theperipheral portion 274. In the embodiment illustrated, the inner end cap262 includes six equally spaced apart projections “T-1” to “T-6.” Thus,in this embodiment, the projections “T-1” to “T-6” are approximately 60°apart. Referring to FIG. 4, the projections “T-1” to “T-6” areconfigured to be received inside the cutout portions “N-1” to “N-6” ofthe caster barrel 228. Because the projections “T-1” to “T-6” areequally spaced apart, the inner end cap 262 may be rotated relative tothe caster barrel 228 in a clockwise (“CW”) direction or acounter-clockwise (“CCW”) direction (identified by double headed arrow290 illustrated in FIGS. 8 and 9) and the projections “T-1” to “T-6”inserted into any of the cutout portions “N-1” to “N-6” of the casterbarrel 228.

Because all of the projections “T-1” to “T-6” are inserted into thecutout portions “N-1” to “N-6” at the same time, for the sake ofclarity, the positioning of the inner end cap 262 relative to the casterbarrel 228 will be described with respect to the position of theprojection “T-1.” However, as appreciated by those of ordinary skill inthe art, when the projection “T-1” is received inside a selected one ofthe cutout portions “N-1” to “N-6,” the other projections “T-2” to “T-6”are received inside corresponding ones of the cutout portions “N-1” to“N-6.”

Because the projection “T-1” may be inserted into any of the cutoutportions “N-1” to “N-6,” in the embodiment illustrated, the inner endcap 262 may be selectively attached to the caster barrel 228 in one ofsix positions. For ease of illustration, the positions will be describedas follows:

Position 1: the projection “T-1” is inside the cutout portion “N-1;”

Position 2: the projection “T-1” is inside the cutout portion “N-2;”

Position 3: the projection “T-1” is inside the cutout portion “N-3;”

Position 4: the projection “T-1” is inside the cutout portion “N-4;”

Position 5: the projection “T-1” is inside the cutout portion “N-5;” and

Position 6: the projection “T-1” is inside the cutout portion “N-6.”

For ease of illustration, it may be helpful to define an absolutecoordinate system using the center of the center through-hole 278 as anorigin for the coordinate system. Referring to FIG. 8, an imaginary line“X” drawn from the origin through the center of the through-hole “A-1”serves as a horizontal axis “X” in the coordinate system. As viewed fromthe outside, the center of the through-hole “A-1” is located at 0°relative to the horizontal axis “X” in the coordinate system. The centerof the through-hole “A-2” is located at 59° relative to the horizontalaxis “X”, the center of the through-hole “A-3” is located at 118°relative to the horizontal axis “X”, the center of the through-hole“A-4” is located at 177° relative to the horizontal axis “X”, the centerof the through-hole “A-5” is located at 236° relative to the horizontalaxis “X”, and the center of the through-hole “A-6” is located at 295°relative to the horizontal axis “X”. As explained above, the inner endcap 262 may be rotated clockwise and/or counter-clockwise relative tothis coordinate system. Thus, the through-holes “A-1” to “A-6” may bepositioned at different angles relative to the horizontal axis “X”depending upon in which of the Positions 1-6 the inner end cap 262 isoriented. Table A below lists the angles of the centers of thethrough-holes “A-1” to “A-6” relative to the horizontal axis “X” foreach of the Positions 1-6. The first column of Table A lists thepositions illustrated in FIG. 8.

TABLE A Through- Position Position Position Position Position Positionhole 1 2 3 4 5 6 A-1  0°  60° 120° 180° 240° 300° A-2  59° 119° 179°239° 299° 359° A-3 118° 178° 238° 298° 358°  58° A-4 177° 237° 297° 357° 57° 117° A-5 236° 296° 356°  56° 116° 176° A-6 295° 355°  55° 115° 175°235°

Thus, in the embodiment illustrated, the through-holes “A-1” to “A-6”may be selectively positioned at the angles provided in Table A aboverelative to the horizontal axis “X.”

Referring to FIGS. 3A-4, the caster mount 264 includes a body portion300 and a graspable portion 304. The body portion 300 is configured tobe received inside the hollow interior 231 of the caster barrel 228 viathe second open end portion 234 and to be rotatable therein. Thegraspable portion 304 configured to be positioned outside the casterbarrel 228 when the body portion 300 is received inside the hollowinterior 231 of the caster barrel 228.

Referring to FIG. 10, the body portion 300 is generally cylindrical inshape having a center portion 310 surrounded by a peripheral portion312. A threaded center aperture 316 is formed in the center portion 310.One or more threaded apertures (e.g., threaded apertures “B-1,” “B-2,”and “B-3”) are formed in the body portion 300. In the embodimentillustrated, three threaded apertures “B-1,” “B-2,” and “B-3” are formedin the peripheral portion 312. The threaded apertures “B-1” and “B-2”are approximately 125° apart. The threaded apertures “B-2” and “B-3” areapproximately 125° apart. The threaded apertures “B-3” and “B-1” areapproximately 110° apart. Thus, the three threaded apertures “B-1,”“B-2,” and “B-3” are not equally spaced apart.

Using the coordinate system defined above, when the threaded centeraperture 316 is aligned with the center through-hole 278 (see FIGS. 8and 9) of the inner end cap 262, the center of the threaded aperture“B-1” is located at approximately 0°. In other words, the center of thethrough-hole “A-1” is aligned with the center of the threaded aperture“B-1.” The center of the threaded aperture “B-2” is located atapproximately 125°. The center of the threaded aperture “B-3” is locatedat approximately 250°.

Optionally, one or more apertures (e.g., apertures “C-1” to “C-5”) areformed in the body portion 300. For example, five apertures “C-1” to“C-5” may be formed in the peripheral portion 312 of the body portion300. These apertures may help reduce the weight of the caster mount 264.In other words, the apertures “C-1” to “C-5” may be included to reducethe overall mass of the caster mount 264. Alternatively, the apertures“C-1” to “C-5” may be threaded like the threaded apertures “B-1,” “B-2,”and “B-3” for purposes of providing smaller increments of adjustment(e.g., increments of adjustment smaller than 1°).

Returning to FIG. 4, the body portion 300 also includes a transversechannel 320 configured to receive the first end portion 181 of theupright pivot pin 180. The transverse channel 320 is configured to limitforward and backward movement of the upright pivot pin 180.

Turning to FIGS. 3A and 3B, a first fastener 330 (such as a threadedbolt) may be used to connect the inner end cap 262 and the caster mount264 together inside the caster barrel 228. For example, the firstfastener 330 may be received inside the center through-hole 278 of theinner end cap 262 and threadedly engage threads (not shown) inside thethreaded center aperture 316 of the caster mount 264. When the uprightpivot pin 180 has been inserted through the slot 240 (see FIG. 4) andinto the transverse channel 320 (see FIG. 4), the first fastener 330passes through the threaded through-hole 183 formed in the first endportion 181 of the upright pivot pin 180. In this manner, the firstfastener 330 retains the upright pivot pin 180 inside the caster mount264 inside the caster barrel 228.

Both the inner end cap 262 and the caster mount 264 may be rotatableabout the first fastener 330. Thus, the first fastener 330 may bealigned along a common axis of rotation for the inner end cap 262 andthe caster mount 264.

A second fastener 334 (such as a threaded bolt) may be received insideone of the through-holes “A-1” to “A-6” of the inner end cap 262 and oneof the threaded apertures “B-1” to “B-3” of the caster mount 264 tolimit rotation of the caster mount 264 relative to the inner end cap262. Thus, the second fastener 334 may be used to maintain the castermount 264 in a selected position relative to the inner end cap 262.Further, when the second fastener 334 is adequately tightened, the innerend cap 262 and the caster mount 264 are drawn together inwardly intothe hollow interior 231 of the caster barrel 228 which further bringsthe projections “T-1” to “T-6” into engagement with the cutout portions“N-1” to “N-6” thereby preventing rotation of the inner end cap 262relative to the caster barrel 228.

The position marker 276 may be used to place the inner end caps 262 ofthe right and left caster mount assemblies 252 and 254 in the sameorientation relative to the caster barrels 226 and 228, respectively.Thus, the right and left caster mount assemblies 252 and 254 provide ameans by which the inner end caps 262 may be readily placed in the sameorientation. Further, depending upon the implementation details, thelocation of the end of the second fastener 334 inside one of thethrough-holes “A-1” to “A-6” may be readily viewed by a user. Thus, theuser need only configure one of the right and left caster mountassemblies 252 and 254 and then copy that configuration on the otherside.

Referring to FIGS. 11-13, as discussed in the Background Section, it isdesirable for the upright pivot pin 180 (see FIGS. 3A-4) to beperpendicular to the support surface 102. For illustrative purposes, areference line “P” that is perpendicular to the support surface 102 hasbeen provided in FIGS. 11-13. The left caster mount assembly 254 may beused to adjust an angle β the upright pivot pin 180 relative to thereference line “P” within a predetermined range of adjustment. Forexample, the left caster mount assembly 254 may provide approximately15° of adjustment. The shape and size of the slot 240 (see FIG. 4) maydetermine at least in part, the size of the predetermined range.However, this is not a requirement.

The left caster mount assembly 254 illustrated is configured to adjustthe angle β of the upright pivot pin 180 in substantially uniformincrements. In the embodiment illustrated, the left caster mountassembly 254 adjusts the angle β of the upright pivot pin 180 in 1°increments. For example, within a 15° predetermined adjustment range(e.g., 15°), the upright pivot pin 180 may be positioned in fifteendifferent positions spaced approximately 1° apart.

As is apparent to those of ordinary skill in the art, the angle β theupright pivot pin 180 relative to the reference line “P” is determinedat least in part by the orientation of the caster mount 264 relative tothe support surface. For illustrative purposes, the rearward mostposition of the upright pivot pin 180 (illustrated in FIG. 11) will bereferred to as 0° within the predetermined range of adjustment. Theforward most position of the upright pivot pin 180 will be referred toas “M°” within the predetermined range of adjustment. In embodiments inwhich the predetermined range of adjustment is about 15°, M is equal to15.

In the embodiment illustrated in the drawings, rotating the caster mount264 in a counter-clockwise direction rotates the upright pivot pin 180forwardly (i.e., toward M°) and rotating the caster mount 264 in aclockwise direction rotates the upright pivot pin 180 rearwardly (i.e.,toward 0°). For example, rotating the caster mount 264 by 1° in thecounter-clockwise direction rotates the upright pivot pin 180 forwardly1°. Similarly, rotating the caster mount 264 by 1° in the clockwisedirection rotates the upright pivot pin 180 rearwardly 1°.

For ease of illustration, when the threaded aperture “B-1” is alignedwith the through-hole “A-1,” the upright pivot pin 180 will be describedas being in the rearward most position (0°) illustrated in FIG. 11. Whenthe predetermined range of adjustment is about 15° and the adjustmentincrement is 1°, the upright pivot pin 180 may be positioned at 0°, 1°,2° . . . 15°.

Referring to Table A above, when the inner end cap 262 is in Position 1,the caster mount 264 may be rotated to align threaded aperture “B-1”with the through-hole “A-1.” As explained above, in this configuration,the upright pivot pin 180 is angled in its most rearward position (0°).This position of the caster mount 264 will referred to as an initialposition. The caster mount 264 may be rotated 7° in thecounter-clockwise direction from the initial position to align thethreaded aperture “B-2” with the through-hole “A-3” (i.e.,125°−7°=118°). Further, the caster mount 264 may be rotated 14° in thecounter-clockwise direction from the initial position to align thethreaded aperture “B-3” with the through-hole “A-5” (i.e.,250°−14°=236°). Thus, when the inner end cap 262 is in Position 1, theupright pivot pin 180 may be positioned at 0°, 7°, and 14°.

When the inner end cap 262 is in Position 2, the threaded aperture “B-1”may be rotated 5° in the counter-clockwise direction from the initialposition to align the threaded aperture “B-1” with the through-hole“A-6” (i.e., 0°−5°=355°). Further, the caster mount 264 may be rotated6° in the counter-clockwise direction from the initial position to alignthe threaded aperture “B-2” with the through-hole “A-2” (i.e.,125°−6°=119°). Further, the caster mount 264 may be rotated 13° in thecounter-clockwise direction from the initial position to align thethreaded aperture “B-3” with the through-hole “A-4” (i.e.,250°−13°237°). Thus, when the inner end cap 262 is in Position 2, theupright pivot pin 180 may be positioned at 5°, 6°, and 13°.

When the inner end cap 262 is in Position 3, the threaded aperture “B-1”may be rotated 4° in the counter-clockwise direction from the initialposition to align the threaded aperture “B-1” with the through-hole“A-5” (i.e., 0°−4°=356°). Further, the caster mount 264 may be rotated5° in the counter-clockwise direction from the initial position to alignthe threaded aperture “B-2” with the through-hole “A-1” (i.e.,125°−5°=120°). Further, the caster mount 264 may be rotated 12° in thecounter-clockwise direction from the initial position to align thethreaded aperture “B-3” with the through-hole “A-3” (i.e.,250°−12°=238°). Thus, when the inner end cap 262 is in Position 3, theupright pivot pin 180 may be positioned at 4°, 5°, and 12°.

When the inner end cap 262 is in Position 4, the threaded aperture “B-1”may be rotated 3° in the counter-clockwise direction from the initialposition to align the threaded aperture “B-1” with the through-hole“A-4” (i.e., 0°−3°=357°). Further, the caster mount 264 may be rotated10° in the counter-clockwise direction from the initial position toalign the threaded aperture “B-2” with the through-hole “A-6” (i.e.,125°−10°=115°). Further, the caster mount 264 may be rotated 11° in thecounter-clockwise direction from the initial position to align thethreaded aperture “B-3” with the through-hole “A-2” (i.e.,250°−11°=239°). Thus, when the inner end cap 262 is in Position 4, theupright pivot pin 180 may be positioned at 3°, 10°, and 11.°

When the inner end cap 262 is in Position 5, the threaded aperture “B-1”may be rotated 2° in the counter-clockwise direction from the initialposition to align the threaded aperture “B-1” with the through-hole“A-3” (i.e., 0°−2°=358°). Further, the caster mount 264 may be rotated9° in the counter-clockwise direction from the initial position to alignthe threaded aperture “B-2” with the through-hole “A-5” (i.e.,125°−9°=116°). Further, the caster mount 264 may be rotated 10° in thecounter-clockwise direction from the initial position to align thethreaded aperture “B-3” with the through-hole “A-1” (i.e.,250°−10°=240°). Thus, when the inner end cap 262 is in Position 5, theupright pivot pin 180 may be positioned at 2°, 9°, and 10.°

When the inner end cap 262 is in Position 6, the threaded aperture “B-1”may be rotated 1° in the counter-clockwise direction from the initialposition to align the threaded aperture “B-1” with the through-hole“A-2” (i.e., 0°−1°=359°). Further, the caster mount 264 may be rotated8° in the counter-clockwise direction from the initial position to alignthe threaded aperture “B-2” with the through-hole “A-4” (i.e.,125°−8°=117°). Further, the caster mount 264 may be rotated 15° in thecounter-clockwise direction from the initial position to align thethreaded aperture “B-3” with the through-hole “A-6” (i.e.,250°−15°=235°). Thus, when the inner end cap 262 is in Position 6, theupright pivot pin 180 may be positioned at 1°, 8°, and 15°.

As discussed in the Background Section, in some wheelchairs, the heightof the seat 138 relative to the support surface 102 may be adjusted.This may be achieved by adjusting the position of the axle assemblies146 of the right and left rear wheels 142 and 144 relative to the frame120. In the embodiment illustrated, each of the right and left rearwheel mounting assemblies 152 and 154 are configured to adjust theposition of the axle assemblies 146 of the right and left rear wheels142 and 144 relative to the frame 120. Specifically, the right rearwheel mounting assembly 152 is configured to selectively raise and lowerthe right side portion 122 of the frame 120 relative to the axleassembly 146 of the right rear wheel 142, and the left rear wheelmounting assembly 154 is configured to selectively raise and lower theleft side portion 124 of the frame 120 relative to the axle assembly 146of the left rear wheel 144 to thereby changing the position of the frame120 relative to the support surface 102.

Referring to FIGS. 14 and 15, adjusting the position of the right rearwheel 142 (see FIG. 1) and the left rear wheel 144 relative to the frame120 changes an angle “a” of the frame 120 relative to the supportsurface 102. For ease of illustration, the angle “a” has been definedbetween the horizontally extending portion 134 of the left supportmember 128 and the support surface 102. Depending upon theimplementation details, an angle of the seat 138 relative to the supportsurface 102 may be approximately equal to the angle “a,” but this is nota requirement.

In FIG. 14, the left rear wheel mounting assembly 154 is configured toposition the axle assembly 146 of the left rear wheel 144 at a firstdistance from the frame 120. While not illustrated in FIG. 14, the rightrear wheel mounting assembly 152 may be configured to position the axleassembly 146 of the right rear wheel 142 at a distance from the frame120 that is substantially equal to the first distance. In thisconfiguration, the upright pivot member 180 (see FIGS. 3A-4) may besubstantially perpendicular to the support surface 102 (i.e., the angle“β” is substantially 0°).

In FIG. 15, the left rear wheel mounting assembly 154 is configured toposition the axle assembly 146 of the left rear wheel 144 at a seconddistance that is greater than the first distance illustrated in FIG. 14.Thus, in FIG. 15, the angle “a” is larger than in FIG. 14. While notillustrated in FIG. 15, the right rear wheel mounting assembly 152 maybe configured to position the axle assembly 146 of the right rear wheel142 at a distance from the frame 120 that is substantially equal to thesecond distance that the axle assembly 146. In this configuration, theupright pivot member 180 (see FIGS. 3A-4) is not substantiallyperpendicular to the support surface 102 (i.e., the angle “β” is greaterthan or less than 0°). When the upright pivot member 180 (see FIGS.3A-4) is not substantially perpendicular to the support surface 102(i.e., the angle “β” is greater than or less than 0°), the left castermount assembly 254 described above may be used to rotate the uprightpivot member forwardly or rearwardly (i.e., to adjust the angle “β”) asappropriate to position the upright pivot member 180 perpendicular tothe support surface 102.

Alternatively, referring to FIGS. 16 and 17, the left bearing forkassembly 174 may be connected to the wheelchair 100 (see FIGS. 1 and 2)by a caster mount assembly 340 that is not configured to adjust theangle of the upright pivot pin 180 relative to the support surface 102.Because the right and left bearing fork assemblies 172 and 174 aremirror images of one another, for the sake of brevity, only the leftbearing fork assembly 174 has been illustrated in FIGS. 16 and 17 andwill be described in detail. However, those of ordinary skill in the artappreciate that the right bearing fork assembly 172 may be connected tothe wheelchair 100 (see FIGS. 1 and 2) by a caster mount assembly thatis substantially similar to or a mirror image of the caster mountassembly 340.

In such embodiments, instead of the caster barrels 226 and 228, aseparate upright collar or caster barrel 350 may be coupled to each ofthe right and left connecting struts 156 and 158. In the embodimentillustrated in FIGS. 16 and 17, the right connecting strut 156 (see FIG.2) is curved and extends between a first caster barrel 350 and thegenerally downwardly extending portion 132 (see FIG. 2) of the rightframe member 126 (see FIG. 2). Similarly, the left connecting strut 158is curved and extends between a second caster barrel 350 and thegenerally downwardly extending portion 136 (see FIG. 2) of the rightframe member 128 (see FIG. 2).

The caster barrel 350 has a substantially hollow tube shape with atransverse threaded through-hole 352 formed in an outer sidewall 354.The sidewall 354 has an open lower end 356 configured to receive thefirst end portion 181 of the upright pivot pin 180 into the interior ofthe caster barrel 350. The inside of the sidewall 354 may include insidethreads (not shown). In this embodiment, the first end portion 181 mayinclude outside threads 357. Thus, the first end portion 181 may bethreaded into the open lower end 356 of the sidewall 354. A set screw358 may inserted into the transverse threaded through-hole 352 tomaintain the upright pivot pin 180 inside the caster barrel 350. In thisembodiment, the transverse threaded through-hole 183 (see FIG. 4) may beomitted from the upright pivot pin 180. A chemical bonding agent oradhesive, such as LOCTITE® 262 Threadlocker, may be used to permanentlybond the threaded first end portion 181 of the upright pivot pin 180inside the caster barrel 350.

The left bearing fork assembly 174 illustrated in FIGS. 16 and 17includes a top cap 360 that differs slightly from the top cap 176 of theleft bearing fork assembly 174 illustrated in FIGS. 3A and 3B.Specifically, the top cap 360 includes a generally dome shaped uppersurface 362, instead of the contoured upper surface 179 of the top cap176.

The foregoing described embodiments depict different componentscontained within, or connected with, different other components. It isto be understood that such depicted architectures are merely exemplary,and that in fact many other architectures can be implemented whichachieve the same functionality. In a conceptual sense, any arrangementof components to achieve the same functionality is effectively“associated” such that the desired functionality is achieved. Hence, anytwo components herein combined to achieve a particular functionality canbe seen as “associated with” each other such that the desiredfunctionality is achieved, irrespective of architectures or intermedialcomponents. Likewise, any two components so associated can also beviewed as being “operably connected,” or “operably coupled,” to eachother to achieve the desired functionality.

While particular embodiments of the present invention have been shownand described, it will be obvious to those skilled in the art that,based upon the teachings herein, changes and modifications may be madewithout departing from this invention and its broader aspects and,therefore, the appended claims are to encompass within their scope allsuch changes and modifications as are within the true spirit and scopeof this invention. Furthermore, it is to be understood that theinvention is solely defined by the appended claims. It will beunderstood by those within the art that, in general, terms used herein,and especially in the appended claims (e.g., bodies of the appendedclaims) are generally intended as “open” terms (e.g., the term“including” should be interpreted as “including but not limited to,” theterm “having” should be interpreted as “having at least,” the term“includes” should be interpreted as “includes but is not limited to,”etc.). It will be further understood by those within the art that if aspecific number of an introduced claim recitation is intended, such anintent will be explicitly recited in the claim, and in the absence ofsuch recitation no such intent is present. For example, as an aid tounderstanding, the following appended claims may contain usage of theintroductory phrases “at least one” and “one or more” to introduce claimrecitations. However, the use of such phrases should not be construed toimply that the introduction of a claim recitation by the indefinitearticles “a” or “an” limits any particular claim containing suchintroduced claim recitation to inventions containing only one suchrecitation, even when the same claim includes the introductory phrases“one or more” or “at least one” and indefinite articles such as “a” or“an” (e.g., “a” and/or “an” should typically be interpreted to mean “atleast one” or “one or more”); the same holds true for the use ofdefinite articles used to introduce claim recitations. In addition, evenif a specific number of an introduced claim recitation is explicitlyrecited, those skilled in the art will recognize that such recitationshould typically be interpreted to mean at least the recited number(e.g., the bare recitation of “two recitations,” without othermodifiers, typically means at least two recitations, or two or morerecitations).

Accordingly, the invention is not limited except as by the appendedclaims.

1. A caster mount assembly comprising: a first rotatable body having afirst plurality of non-uniformly spaced apart apertures; a secondrotatable body having a second plurality of non-uniformly spaced apartapertures, the first rotatable body and the second rotatable body beingrotatable relative to one another along a common axis of rotation toalign a selected one of the first apertures with a selected one of thesecond apertures; a first coupler configured to non-rotatably couple thefirst rotatable body to the second rotatable body after the selected oneof the first apertures has been aligned with the selected one of thesecond apertures; and a bearing fork assembly non-rotatably coupled tothe second rotatable body for rotation therewith.
 2. The caster mountassembly of claim 1, further comprising: a second coupler configured torotatably couple the first rotatable body to the second rotatable body,the first coupler being configured to allow the first and secondrotatable bodies to rotate relative to one another about the common axisof rotation to position the first rotatable body relative to the secondrotatable body.
 3. The caster mount assembly of claim 1, wherein thefirst plurality of non-uniformly spaced apart apertures are positionedin a first substantially circular arrangement and comprise: a firstaperture; a second aperture spaced about 59 degrees from the firstaperture within the first substantially circular arrangement; a thirdaperture spaced about 59 degrees from the second aperture within thefirst substantially circular arrangement; a fourth aperture spaced about59 degrees from the third aperture within the first substantiallycircular arrangement; a fifth aperture spaced about 59 degrees from thefourth aperture within the first substantially circular arrangement; anda sixth aperture spaced about 59 degrees from the fifth aperture withinthe first substantially circular arrangement, the sixth aperture spacedabout 65 degrees from the first aperture within the first substantiallycircular arrangement.
 4. The caster mount assembly of claim 3, whereinthe second plurality of non-uniformly spaced apart apertures arepositioned in a second substantially circular arrangement and comprise:a first aperture; a second aperture spaced about 125 degrees from thefirst aperture within the second substantially circular arrangement; anda third aperture spaced about 125 degrees from the second aperturewithin the second substantially circular arrangement, the third aperturespaced about 110 degrees from the first aperture within the secondsubstantially circular arrangement.
 5. The caster mount assembly ofclaim 4, wherein the first rotatable body comprises a first centralaperture positioned on the common axis of rotation, the second rotatablebody comprises a second central aperture positioned on the common axisof rotation, and the caster mount assembly further comprises: anelongated fastener extending along the common axis of rotation, thefastener extending through the first central aperture and into thesecond central aperture to rotatably couple the first rotatable body tothe second rotatable body, the fastener allowing the first and secondrotatable bodies to rotate relative to one another about the common axisof rotation to position the first rotatable body relative to the secondrotatable body.
 6. The caster mount assembly of claim 1, wherein thefirst rotatable body comprises a marker portion indicating theorientation of the first rotatable body.
 7. A wheelchair for use onsupport surface, the wheelchair comprising: a frame; a first casterbarrel coupled to the frame, the first caster barrel having a firstsubstantially cylindrically shaped sidewall, the first sidewall having afirst open end opposite a second open end and a slot positioned betweenthe first and second open ends; a first rotatable body having a firstportion receivable inside the first open end of the first sidewall ofthe first caster barrel, the first portion of the first rotatable bodybeing rotatable inside the first open end of the first sidewall of thefirst caster barrel about a first axis of rotation, the first rotatablebody comprising a first plurality of non-uniformly spaced apartapertures; a second rotatable body having a first portion receivableinside the second open end of the second sidewall of the first casterbarrel, the first portion of the second rotatable body being rotatableinside the second open end of the first sidewall of the first casterbarrel about the first axis of rotation, the second rotatable bodycomprising a second plurality of non-uniformly spaced apart aperturesand a transverse aperture adjacent the slot of the first sidewall of thefirst caster barrel when the first portion of the second rotatable bodyis received inside the second open end of the first sidewall of thefirst caster barrel; a first fastener configured to non-rotatably couplea selected one of the first apertures with a selected one of the secondapertures; and a first bearing fork assembly having a portion extendinginto the slot of the first sidewall of the first caster barrel and intothe transverse aperture of the second rotatable body, the portion of thefirst bearing fork assembly being coupled inside the transverse apertureof the second rotatable body for rotation with the second rotatable bodyas the second rotatable body rotates inside the second open end of thefirst sidewall of the first caster barrel to determine an angle of thefirst bearing fork assembly relative to the support surface.
 8. Thewheelchair of claim 7, wherein the first rotatable body has a graspableportion non-rotatably coupled to the first portion, the graspableportion being positioned outside the first sidewall of the first casterbarrel and configured to be gripped and rotated to align the selectedone of the first apertures with the selected one of the secondapertures.
 9. The wheelchair of claim 7, wherein the second rotatablebody has a graspable portion non-rotatably coupled to the first portion,the graspable portion being positioned outside the first sidewall of thefirst caster barrel and configured to be gripped and rotated to alignthe selected one of the second apertures with the selected one of thefirst apertures.
 10. The wheelchair of claim 7, wherein the firstapertures are positioned such that at least a selected one of the firstapertures is alignable with at least one of the second apertures everyone degree of rotation about the first axis of rotation within apredetermined range of adjustment.
 11. The wheelchair of claim 10,wherein the predetermined range of adjustment is approximately fifteendegrees.
 12. The wheelchair of claim 7, wherein the first plurality ofnon-uniformly spaced apart apertures are positioned in a firstsubstantially circular arrangement and comprise: a first aperture; asecond aperture spaced about 59 degrees from the first aperture withinthe first substantially circular arrangement; a third aperture spacedabout 59 degrees from the second aperture within the first substantiallycircular arrangement; a fourth aperture spaced about 59 degrees from thethird aperture within the first substantially circular arrangement; afifth aperture spaced about 59 degrees from the fourth aperture withinthe first substantially circular arrangement; and a sixth aperturespaced about 59 degrees from the fifth aperture within the firstsubstantially circular arrangement, the sixth aperture being spacedapart from the about 65 degrees from the first aperture.
 13. Thewheelchair of claim 12, wherein the second plurality of non-uniformlyspaced apart apertures are positioned in a second substantially circulararrangement and comprise: a first aperture; a second aperture spacedabout 125 degrees from the first aperture within the secondsubstantially circular arrangement; and a third aperture spaced about125 degrees from the second aperture within the second substantiallycircular arrangement, the third aperture spaced about 110 degrees fromthe first aperture within the second substantially circular arrangement.14. The wheelchair of claim 7, wherein the first rotatable bodycomprises a first central aperture positioned on the first axis ofrotation, the second rotatable body comprises a second central aperturepositioned on the first axis of rotation, and the wheelchair furthercomprises: an elongated fastener extending along the first axis ofrotation, the fastener extending through the first central aperture andinto the second central aperture to rotatably couple the first rotatablebody to the second rotatable body, the fastener allowing the first andsecond rotatable bodies to rotate relative to one another about thefirst axis of rotation to position the first rotatable body relative tothe second rotatable body.
 15. The wheelchair of claim 7, wherein aplurality of cutout portions are formed in the first open end of thefirst sidewall of the first caster barrel, and the first rotatable bodycomprises a plurality of projections configured to be received insidethe cutout portions to non-rotatably connect the first rotatable body tothe first open end of the first sidewall of the first caster barrel. 16.The wheelchair of claim 15, wherein the cutout portions are spaced apartuniformly along the first open end of the first sidewall of the firstcaster barrel.
 17. The wheelchair of claim 7, wherein the firstrotatable body comprises a marker portion indicating the orientation ofthe first rotatable body relative to the first caster barrel.
 18. Thewheelchair of claim 7, further comprising: a second caster barrelcoupled to the frame, the second caster barrel having a secondsubstantially cylindrically shaped sidewall, the second sidewall havinga first open end opposite a second open end and a slot positionedbetween the first and second open ends; a third rotatable body having afirst portion receivable inside the first open end of the secondsidewall of the second caster barrel, the first portion of the thirdrotatable body being rotatable inside the first open end of the secondsidewall of the second caster barrel about a second axis of rotation,the third rotatable body comprising a third plurality of non-uniformlyspaced apart apertures; a fourth rotatable body having a first portionreceivable inside the second open end of the second sidewall of thesecond caster barrel, the first portion of the fourth rotatable bodybeing rotatable inside the second open end of the second sidewall of thesecond caster barrel about the second axis of rotation, the fourthrotatable body comprising a fourth plurality of non-uniformly spacedapart apertures and a transverse aperture adjacent the slot of thesecond sidewall of the second caster barrel when the first portion ofthe fourth rotatable body is received inside the second open end of thesecond sidewall of the second caster barrel; a second fastenerconfigured to non-rotatably couple a selected one of the third apertureswith a selected one of the fourth apertures; and a second bearing forkassembly having a portion extending into the slot of the second sidewallof the second caster barrel and into the transverse aperture of thefourth rotatable body, the portion of the second bearing fork assemblybeing coupled inside the transverse aperture of the fourth rotatablebody for rotation with the fourth rotatable body as the fourth rotatablebody rotates inside the second open end of the second sidewall of thesecond caster barrel to determine an angle of the second bearing forkassembly relative to the support surface.
 19. The wheelchair of claim18, wherein the first rotatable body comprises a first marker portionindicating the orientation of the first rotatable body relative to thefirst caster barrel and the third rotatable body comprises a secondmarker portion indicating the orientation of the third rotatable bodyrelative to the second caster barrel.
 20. The wheelchair of claim 18,wherein the first bearing fork assembly comprises a first fork rotatablycouplable to a first wheel, the first fork having one tine or a pair ofspaced apart tines, and the second bearing fork assembly comprises asecond fork rotatably couplable to a second wheel, the second forkhaving one tine or a pair of spaced apart tines.
 21. The wheelchair ofclaim 7, further comprising: a first rear wheel coupled to the frame andconfigured to be positionable relative thereto; and a second rear wheelcoupled to the frame and configured to be positionable relative thereto,the positions of the first and second rear wheels relative to the framedetermining at least in part an angle of the frame relative to thesupport surface.
 22. The wheelchair of claim 7, wherein the firstbearing fork assembly comprises a mono-fork rotatably couplable to afirst front wheel by a first axle, the mono-fork comprising a singletine having a threaded aperture with inside threads formed therein, thefirst axle having a threaded distal end portion with outside threadsformed thereon configured to threadedly engage the inside threads of thethreaded aperture.
 23. The wheelchair of claim 22, wherein the firstbearing fork assembly further comprises an end cap and a fastener havingoutside threads formed thereon, the first axle having a proximal endportion with inside threads formed therein configured to be threadedlyengaged the outside threads of the fastener, the fastener beingconfigured to position the end cap against a side portion of the firstfront wheel to maintain the first front wheel on the first axle.
 24. Thewheelchair of claim 22, wherein the mono-fork comprises a substantiallycylindrically shaped collar portion coupled to the tine, the collarhaving an outside circumferentially extending groove formed therein, andthe wheelchair further comprises a bumper configured to be receivedinside the groove, the portion of the first bearing fork assemblyextending into the slot of the first sidewall of the first caster barrelextending through the collar and being rotatably coupled thereto. 25.The wheelchair of claim 7, wherein the first bearing fork assemblycomprises a mono-fork rotatably couplable to a first front wheel by afirst axle, the mono-fork comprising a single tine having a threadedaperture with inside threads formed therein, the first axle having athreaded distal end portion permanently bonded inside the threadedaperture.